Analysis Model and Strength Prediction Method of Wing Crack Propagation Considering Influence of Crack Inclination Angle

To investigate the deformation and failure characteristics of loaded sandstone under the influence of fracture dip angles and characterizing the propagation patterns of wing cracks in fractured rocks, the stress-strain characteristics and failure modes of sandstone samples with different fracture dip angles were analyzed through uniaxial compression tests.A wing crack propagation model in fractured rocks was established based on relevant theories of fracture mechanics.Further, a rock strength calculation method that considers the influence of fracture dip angles was proposed by combining the M-C strength criterion and the Box-Lucas1 function and validated by experimental data.Results show a close match between theoretical and experimental results.As the distance between the wing crack initiation position and the fracture end increases, the fracture dip angle increases while the wing crack initiation angle decreases first, then increases, and finally shows a single descending trend.When the fracture dip angle increases, the longitudinal difference between the peak strength curves first rises and then drops.The conclusions obtained in this study provide theoretical basis and technical support for the stability assessment and engineering application of fractured rocks.